DESCRIPTION (provided by application): Posttraumatic stress disorder (PTSD) is a chronic and debilitating condition, with lifetime prevalence rates ranging from 8%-14% of the US population. Thus, the development of efficacious and cost-effective treatments for PTSD is imperative. Both prolonged exposure therapy (PE) and sertraline (MED) are of established efficacy for PTSD. Yet, we know very little about the comparable effectiveness of these forms of treatment, nor what factors influence treatment acceptance/refusal and completion/drop-out. In this five-year, two-site study, we will examine these issues. This collaborative R01 grant will be conducted at the University of Washington under the direction of Dr. Zoellner and at Case Western Reserve University under the direction of Dr. Feeny. We will conduct a hybrid efficacy-effectiveness trial in which female and male trauma victims will be randomly assigned to either choice or no choice treatment conditions. In the choice condition, participants will choose between prolonged exposure and sertraline. In the no choice condition, participants will be randomly assigned to either prolonged exposure or sertraline. Outcome, as measured by both psychopathology and broader functioning measures, will be assessed through 24-month follow-up. The results of the proposed research will inform clinicians about the relative short-term and long-term effectiveness of PE and MED, provide information about how these treatments influence broader measures of functional impairment, provide information regarding decision making factors in order to maximize treatment utilization, and provide important information about cost effectiveness of both PE and MED for chronic PTSD.